Drilling jig



J. F. -FETTERLY.

DRILLING JIG.=

APPLICATION FILED DEC. 18. i919- 1,430,895. m Patented Oct. 3, 1922.

DRILLING J16}.

Application filed December 18, 191:.

Serial No. 345,864.

(FILED UNDER THE Aer or'nnncn 3, 1883, 22 STAT. L, 625.

To all whom it may concern:

e it known that 1, JOHN F. Fn'r'rnnLY, a citizen of tile United States, dent of ltoona, county of Blair,State of Pennsylv a, have invented an Improvenient in Drilling digs, of which the following is a specification.

The invention described herein may be used by the Government, or any of its oflicers or employees in prosecution of work for the Government, or by any other person in the United States, without payment of any royalty thereon.

This invention relates to a intended to he used as a guide or brace for the shank or arbor of a. hollow mill in removing transverse or longitudinal test bars from the vorlr, such as a cannon; and f'liinctions to prevent "he tool and shank from springing away from the work during the drilling op-- oration.

One object of the invention is to provite a drilling which will be e homely simple in construction, thoroughly efficient in operation, and durable in use.

ll it-h this object in view, and. others appearing as the specification proceeds and the nature of the invention is more fully disclosed, the invention res'lcs. generally stated, in a drilling jig comprisinguprights,

crossbar or bridge adjustable on said uprights. a bushing holder adjustably carried by said bridge, and bushings disposed in said holder.

More specifically, the invention resides, inter alia, in certain specific improvements in the cross-bar, that is, in a generally cur- 'ilincar crossd'iar conforming to the circumferential contour of the cannon to be dril ed and transversely serratcitl on both sides or fa es for engagement with a correspomliuglv serrnl'el'l washer employed in scouring 7 the l'mslung holder on the arched crossbar, against movement longitudinally thereof.

The invention resides, finally in certain refinements of construction and felicitous combinations and arrangements of structural parts, as will be fully understood as the specification proceeds.

The accompanying drawings graphically disclose an exemplary concrete or physical embodiment of the underlying principles of and a resi looking at the serrated face thereof; and

Fig. 5 is a detail view of a modified form of bushing holder.

Referring, now, in detail to the drawing l. 1 designates uprights, which may be advantageously screws, as shown, each of which may be conveniently supported, at its lower end. in a base. preferably a casting comprising the base proper 2, having vertical ribs 3 rising therefrom and radiating from a central, verticalrecessed hub 4:. The screws 1 are provided, at their lower terminals, with threadedportions 5, adapted to be threaded into the bore of the hub, in which the screws are held against turning by the headless screws 5, which are threaded through apertures formed in the hubs and into a recess in the portions 5, or otherwise. The bases supporting the screws be advantageously clamped to the platen of the machine which drives the tool.

6 indicates a cross-bar or bridge, which is generally arched or curvilinear, as shown, conforming to the circumferential contour of the cannon, or other work to be drilled, so that, as it were. it cradles the cannon. as clearly shown in Figure 1. The two sides or faces of the crossbar are preferably Flat. and are transversely serrated, as shown at 7. for a purpose presently appearing. The crossbar is also provided with a longitudinally extending slot 8, also for a purpose presently appearing. The cross-bar is provided with bent apertm'ed terminals 0, 9, the apertures thereof loosely fitting the screws 1, 1. Adjusting or feed nuts 10, 10 are carried by the screws 1, 1, and clamp ing nuts 10, 10 secure the cross-bar in adjusted position. Projecting through the slot 8 of the cross-bar 6 is a bushing holder comprising, in this instance, a head 11 having an opening l2 therethrough and a shank l3 projecting from said head and passing through said slot.

Between the head 11 and the cross-bar 6 is disposed a washer 1d serrated on one face thereof, as shown at 15. Conveniently, the washer may be secured to the head 11 by pins or screws 16 passing through openings 1'? and into the head 11.

A second washer 18 is placed over the shank 18 and against the opposite face of the crossbar 6. This washer may be likewise serrated, as shown, on one face, it desired. or may be a plain washer of conventional form. I

A clamp nut 19 is screwedon the threaded end 20 of the shank 13, and clamps the holder in position at any point of adjustment thereof lengthwise of the bridge 6.

As will be evident, the serrations on the plate 14, engaging with those on the bridge 6, will draw the bushing holder into position so that, when the holder is secured, the longitudinal axis of the arbor will be vertical.

While I have described and shown both faces of the bridge 6 as serrated, it is to be understood that it is necessary, to serrate one face only.

Telescoping bushings 21, 22 are disposed in the bushing holder, the bushing 21 being held against rotation by a pin 23 carried thereby and entering a recess in the bushing holder, as shown in Figure 1, and the bushing 22 being split. The spindle 24 forms no part of my invention, and may be of conventional form. The spindle carries, as usual, the drill 25.

Having thus fully described my invention, it will be seen that, by my construction of a jig, the drilling tool 25 and the shank or spindle 24 are held against springing away from the work A during operation; and it will also be rec gnized that the apparatus is extremely simple in con struction and thoroughly practical in use.

Figure 5 discloses a slight modification, in respect to the bushing holder 11. In this instance, the holder is provided with a serrated face 1%, which serves the same function as the washer 1 1, shown in Figures 2, 3 and 4, thus dispensing with; the use of said washer.

lVhat I claim and desire to secure by Letters Patent, is

1. A drilling jig, including supports, a bridge mounted on said supports, the vertical faces of said bridge serrated and said. bridge provided with a longitudinal slot, means for adjusting the bridge vertically on the supports, a bushing holder mounted on the bridge and having a shank passing through the slot and means carried by the holde' and co-operating with the serrated face of the bridge to secure the holder in adjusted positions on said bridge.

2. A drilling jig, including supports, a bridge mounted on said supports, said bridge provided with a longitudinal slot, means for adjusting the bridge vertically on the supports, a bushing holder formed with a shank passing horizontally through the slot and means for clamping the holder in adjusted positions on the bridge.

JOHN F. FETTERLY. 

